Insulating tape for battery and preparation method of insulating tape

Abstract

The invention relates to the technical field of auxiliary materials for battery manufacturing, and discloses an insulating tape for a battery and a preparation method of the insulating tape. The preparation method specifically comprises the following steps: S11, glue preparation: in an environment with controlled temperature and humidity, putting an adhesive, insulating powder and an auxiliary agent into high-speed dispersion equipment for premixing at normal pressure, and then continuously dispersing for 30-60 minutes under the conditions that the vacuum degree is-0.05 to-0.08 MPa and the rotating speed is 1000-2000r / min to obtain homogeneous insulating glue; and S12, coating: quantitatively coating the prepared insulating glue on a preset treatment surface of a base material in a micro gravure coating manner. The single-sided roughened base material subjected to corona treatment is adopted, the mechanical embedding and chemical binding force of the base material and the adhesive layer is remarkably enhanced, a nano boron nitride / mica powder compound system coated with a silane coupling agent is introduced as insulating powder, the dielectric strength, thermal conductivity and compactness are improved, and the thermal conductivity of the adhesive layer is improved. And the bottlenecks of insulation reliability, safety and durability are systematically solved from the material level.

Description

Technical Field

[0001] This invention relates to the technical field of auxiliary materials for battery manufacturing, and more specifically, to an insulating tape for batteries and its preparation method. Background Technology

[0002] With the rapid development of new energy vehicles, energy storage power stations, and portable electronic devices worldwide, secondary batteries such as lithium-ion batteries, as core power and energy storage units, have increasingly higher requirements for energy density, safety, and cycle life. Inside the battery, from tiny cells to large battery pack modules, there are many parts that require electrical isolation and physical protection, such as battery tabs (positive and negative leads), between cells, and between cells and the metal casing. Insulating tape plays a crucial role here, and its performance is directly related to the battery's insulation safety, thermal management efficiency, and long-term reliability.

[0003] Currently, most battery insulating tapes on the market are adaptations of traditional pressure-sensitive tape technology. A common approach is to use polyester film (PET) or polyimide film (PI) as the substrate, coating it with an acrylic or rubber-based pressure-sensitive adhesive. To improve insulation, some products add inorganic fillers such as calcium carbonate, silica, or ordinary aluminum hydroxide to the adhesive layer. In terms of manufacturing processes, conventional scraping or roller coating methods are mostly used for application, followed by tunnel oven drying. These existing technologies meet basic insulation and fixation requirements to a certain extent, but their designs are often rather crude and lack systematic optimization for the harsh application environments of batteries.

[0004] Currently, the problems hindering the development of higher performance battery insulating tapes include: (1) The overall insulation reliability of existing tapes is insufficient. During long-term charging and discharging of batteries and high and low temperature cycling, due to the poor compatibility between the adhesive components and the electrolyte, swelling, plasticization or chemical degradation occur, resulting in a significant decrease in volume resistivity and dielectric strength. At the same time, the interface bonding between the inorganic filler and the polymer matrix of simple physical blend is weak. Under stress or swelling, it is easy to generate interfacial microcracks or debonding, forming conductive channels and accelerating the deterioration of insulation performance. (2) Most insulating tapes only focus on electrical isolation and do not give enough consideration to the passive flame retardant function that is crucial in the early stage of battery thermal runaway. The substrate itself may have a certain flame retardancy, but the adhesive layer is often a flammable organic polymer. Once ignited, it will become a path for flame propagation and cannot provide an effective barrier to suppress the spread of battery heat. (3) The internal environment of the battery is complex. The tape needs to adhere to the surface of multiple materials such as metal, plastic and coating at the same time and withstand different degrees of deformation. After long-term high temperature and high humidity aging or cold and heat shock, the existing tape is prone to adhesion decay, cohesion damage of the adhesive layer or peeling from the substrate, losing the sealing and fixing function, which may lead to loosening of parts and short circuit risk. Based on the above, there is an urgent need to develop a high-performance battery insulating tape that incorporates comprehensive and systematic innovation from formulation design to manufacturing process in order to solve the aforementioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to provide an insulating tape for batteries and its preparation method. By using a single-sided roughened substrate treated with corona, the mechanical interlocking and chemical bonding force between the substrate and the adhesive layer are significantly enhanced, effectively preventing delamination. A flame-retardant acrylic pressure-sensitive adhesive with a limiting oxygen index ≥28% is designed as the adhesive to impart flame retardancy to the adhesive layer itself, achieving the V-0 flame retardant standard in synergy with the substrate.

[0006] This invention is achieved through a method for preparing insulating tape for batteries, specifically comprising the following steps: S11. Adhesive preparation: Under controlled temperature and humidity, the adhesive, insulating powder and additives are put into a high-speed dispersion device and premixed under normal pressure. Then, the mixture is continuously dispersed for 30-60 minutes under a vacuum of -0.05 to -0.08 MPa and a rotation speed of 1000-2000 r / min to obtain a homogeneous insulating adhesive. S12. Coating: The prepared insulating adhesive is quantitatively coated onto the pre-treated surface of the substrate using a micro-gravure coating method, and the thickness of the wet adhesive coating is controlled to be 20-50μm. S13. Preliminary drying: The coated substrate is sent into the first drying tunnel and baked at a temperature of 80-110℃ to dry the adhesive layer to obtain a semi-finished product after preliminary drying. S14. Heat curing: The semi-finished product after preliminary drying is sent into the second drying tunnel and heat-cured at 120-150℃ for 2-5 minutes. S15. Winding and Slitting: The fully cured and cooled tape is wound and slid to obtain the finished battery insulating tape.

[0007] Furthermore, in a temperature and humidity controlled environment (S11), the adhesive, insulating powder, and additives are premixed in a high-speed dispersion device under normal pressure. The temperature and humidity controlled environment includes: Before preparing the adhesive, the raw materials and equipment are placed in a constant temperature and humidity clean room at a temperature of 23±2℃ and a relative humidity of ≤50%RH for at least 4 hours to ensure that the physical properties of the adhesive and powder raw materials are stable before mixing, and to prevent the insulating powder from absorbing moisture or the adhesive from undergoing a pre-reaction due to excessive environmental humidity, thus ensuring the batch stability and shelf life of the final adhesive. In the premixing stage, the liquid adhesive is first pumped into the dispersion vessel. After stirring is started, the pre-dried insulating powder and the additives are slowly and evenly added under normal pressure and medium speed of 500-800 r / min. The feeding process should be controlled within 5-8 minutes. Then, the stirring speed is maintained for another 10 minutes to allow the solid powder to be initially wetted and coated by the liquid, forming a suspension system.

[0008] Furthermore, the high-speed dispersion equipment includes a high-speed planetary disperser with a jacket through which circulating cooling water can pass and a high-speed dispersion vessel with a vacuum-sealed lid. During the vacuum dispersion process, the material generates heat due to high-speed shearing. The cooling water in the jacket keeps the material temperature below 40°C to prevent the temperature from being too high, which could cause the adhesive to cross-link prematurely or the solvent to evaporate excessively and change the formula ratio. Obtaining a homogeneous insulating adhesive involves: after completing the specified dispersion time, stopping the machine, breaking the vacuum, taking a sample and coating it onto a glass plate for observation. Under a 100x magnifying glass, no visible undispersed powder particles or gel particles are observed, and the adhesive exhibits a homogeneous fluid state without bubble stratification. Simultaneously, its viscosity is measured using a rotational viscometer in a 25°C constant temperature water bath, and the reading should be stable within the range of 3000-8000 cP, ensuring that the adhesive has good transferability and leveling properties in the subsequent microgravure coating process.

[0009] Further, in S12, the prepared insulating adhesive is quantitatively coated onto the pre-treated surface of the substrate using a microgravure coating method, including: The component used in the microgravure coating method for the prepared insulating adhesive is an anilox roller. The anilox roller has a screen count of 150-250 LPI and controls the corresponding dot engraving depth to be 30-60 μm. This allows for precise control of the amount of adhesive transferred per unit area, ensuring that the wet adhesive coating thickness is within the range of 20-50 μm. The pre-treatment of the substrate refers to the single-sided surface modification treatment of the selected polyester film substrate before the coating process. Through corona treatment, the treatment power is set to 8-15kW and the electrode spacing is 1-2mm, so that the surface roughness Ra value of the treated surface reaches 0.1-1.0μm and the surface energy is increased to 50dyn / cm, which improves the spreading and anchoring effect of the adhesive.

[0010] Furthermore, before the S12 coating operation, the prepared insulating adhesive must be filtered through a precision filter equipped with a 100-200 mesh stainless steel filter to remove trace mechanical impurities or large aggregates of powder that may be introduced during the dispersion and transfer process. During the quantitative coating process in S12, the operating parameters of the coating machine need to be controlled in a coordinated manner to stabilize the coating speed within the range of 10-30m / min. Simultaneously, the angle and pressure of the doctor blade on the anilox roller are precisely adjusted to control the pressure within the range of 0.2-0.5MPa. At the same time, the substrate tension between the unwinding and coating sections is controlled in a closed loop by a tension sensor to ensure that the adhesive coating transferred from the anilox roller to the rough substrate is continuous, uniform, and without streaks.

[0011] Further, in S13, the coated substrate is fed into the first drying tunnel and baked at a controlled temperature of 80-110°C to allow the adhesive layer to dry to the surface, including: The first drying tunnel is a hot air circulating tunnel-type drying oven with a length between 8 and 15m and multiple independent temperature zones. Its internal hot air temperature adopts a gradient design, gradually increasing from the inlet end near the coating machine to the outlet end. The overall temperature increase is controlled at 80-110℃, so that the solvent or water in the adhesive layer can evaporate slowly and fully from the surface to the inside, avoiding the formation of bubbles or coating collapse due to the internal solvent retention caused by the surface drying too fast. The process goal of making the adhesive layer surface dry is that after baking for 1-3 minutes in this stage, the fluidity of the adhesive layer surface disappears and a slight indentation is left that can slowly rebound. At this time, the adhesive layer still contains a small amount of residual solvent and has the ability to deform.

[0012] Further, in S14, the pre-dried semi-finished product is sent to the second drying tunnel, where it undergoes heat curing treatment at a controlled temperature of 120-150℃ for 2-5 minutes, including: The second drying tunnel is an infrared radiation heating tunnel, which can provide uniform radiant heat, so that the inside and outside of the adhesive layer are heated to a constant high temperature of 120-150℃, which is conducive to the thorough removal of internal solvents. The thermosetting process includes: using a constant high-temperature treatment environment to completely evaporate the 2-5% residual solvent or small molecule volatiles that remain deep in the adhesive layer after preliminary drying, so that the adhesive layer is completely densified. Moreover, the temperature range of the constant high-temperature treatment environment can effectively activate the chemical reactivity of the curing agent, promote the full cross-linking reaction between adhesive molecules, and improve the cohesive strength, heat resistance and electrolyte resistance of the adhesive layer.

[0013] Further, in S15, the fully cured and cooled tape is wound and slit, including: The winding process is completed on a winding machine with a precision tension control system. The winding tension is automatically set and maintained at a constant 10-50N according to the width of the tape, ensuring that the tape is tightly wound and neatly rolled. The winding method adopts center winding, and at the same time as winding, a layer of anti-stick release film must be simultaneously lined on the surface of the tape adhesive layer to prevent the layers of the tape from sticking together when stored in rolls. The slitting process involves longitudinally dividing the large roll of finished product into strips according to a pre-set precise width on a high-speed CNC slitting machine. The smoothness of the slitting edges is monitored in real time during the slitting process to ensure that there are no burrs or glue layer flips.

[0014] Compared with the prior art, the battery insulating tape and its preparation method provided by the present invention have the following beneficial effects: 1. By using a single-sided roughened substrate treated with corona, the mechanical interlocking and chemical bonding between the substrate and the adhesive layer are significantly enhanced, effectively preventing delamination. A flame-retardant acrylic pressure-sensitive adhesive with a limiting oxygen index ≥28% is designed as the adhesive to impart flame retardancy to the adhesive layer itself, achieving the V-0 flame retardant standard in synergy with the substrate. Furthermore, a nano-boron nitride / mica powder composite system coated with a silane coupling agent is introduced as the insulating powder, improving dielectric strength, thermal conductivity, and density. This systematically solves the bottlenecks in insulation reliability, safety, and durability from a material perspective. 2. Through highly refined and parameter-controllable preparation processes, material innovation is transformed into stable and superior product performance. Vacuum high-speed dispersion and cooling temperature control ensure highly homogeneous and defect-free dispersion of insulating powder in the adhesive. Microgravure coating with specific parameters of 150-250 LPI and 30-60 μm, combined with stepped gradient drying and segmented thermosetting processes, achieves precise control of adhesive layer thickness, gradual and complete solvent evaporation, and full cross-linking reaction. This not only ensures extremely high consistency between product batches but also maximizes the function of each component. The resulting insulating tape exhibits excellent comprehensive performance, maintaining stable high insulation resistance ≥1000 MΩ and adhesion in a wide temperature range of -40℃ to 130℃ and harsh environments. It also has excellent resistance to electrolyte corrosion, thermal shock resistance, and flame propagation delay capabilities, greatly improving the long-term safety and reliability of the battery system.

[0015] Mechanism of action This technical solution involves introducing phosphorus- and nitrogen-containing reactive monomers into the molecular chain or adding halogen-free flame retardants to the system. From a molecular perspective, under high temperature or flame conditions, phosphorus-based flame retardants will rapidly decompose to generate highly dehydrating substances such as polyphosphoric acid, which promotes the dehydration and carbonization of the polymer matrix, forming a dense, heat-insulating, and oxygen-isolated expanded carbon layer. At the same time, nitrogen-based components decompose to produce non-combustible gases such as ammonia and nitrogen, which dilute the concentration of combustible gases and oxygen. More importantly, these flame-retardant elements can capture a large number of high-energy free radicals such as H· and HO· that propagate the flame in the combustion chain reaction during the decomposition process, converting them into substances with lower activity, thereby effectively interrupting the combustion chain reaction at the molecular level and achieving gas-phase flame retardancy. Corona treatment of polyester film substrates involves bombarding their surface with high-energy particles. At the molecular level, this high-energy treatment can break chemical bonds such as CH and CC on the film surface, forming a large number of free radicals. These free radicals then react with oxygen and nitrogen in the air, introducing polar oxygen-containing functional groups such as hydroxyl (-OH), carboxyl (-COOH), and carbonyl (C=O). These newly introduced polar groups can form strong hydrogen bonds, dipole-dipole interactions, and even chemical reactions to form covalent bonds with the polar groups on the adhesive polymer chain. This strong molecular-level interaction, combined with the physical interlocking effect provided by the rough surface, greatly enhances the interfacial bonding energy between the substrate and the adhesive layer. Silane coupling agent surface coating treatment of nano-boron nitride (h-BN) and mica powder results in the partial hydrolysis of the alkoxy group (-Si(OC2H5)3) in the silane coupling agent molecule, which then undergoes a condensation reaction with the hydroxyl group (-OH) on the powder surface to form a strong Si-OM covalent bond. Simultaneously, the organic functional group at the other end of the silane coupling agent reacts chemically or interacts strongly with the carboxyl group in the acrylate polymer chain. In this way, the silane coupling agent constructs a stable "molecular bridge" between the inorganic powder and the organic polymer, greatly improving the originally hydrophobic polymerization. The interfacial compatibility between the material and the hydrophilic inorganic powder reduces dielectric breakdown points caused by interfacial defects and stress concentration. The combination of nano-boron nitride and flake mica powder, with the mica flakes arranged in parallel in the adhesive layer, forces the current attempting to penetrate the adhesive layer to travel along a tortuous path. The nano-boron nitride dispersed in the flake structure has high sp² hybridized BN bond binding energy in its hexagonal crystal system, and the electrons are tightly bound and have extremely low electron mobility, providing extremely high intrinsic insulation. At the same time, its high in-plane phonon conductivity can rapidly dissipate local hotspot heat. Vacuum high-speed dispersion not only physically breaks up powder agglomeration, but more importantly, the vacuum environment eliminates air interference. Oxygen is an inhibitor of free radical polymerization, and moisture may react with the curing agent to generate CO2, causing bubbles or consuming the curing agent. The vacuum environment ensures the chemical purity of the dispersion process, making the subsequent curing reaction controllable. The step-drying and segmented thermal curing process precisely controls the solvent evaporation kinetics and cross-linking reaction kinetics. Low-temperature step-drying allows the solvent to diffuse slowly from the inside of the adhesive layer to the surface for evaporation, avoiding micropores or internal stresses caused by the polymer molecular chains not having enough time to relax and arrange due to excessively rapid evaporation. The subsequent high-temperature curing stage provides sufficient activation energy to ensure that the cross-linking agent and the active groups on the polymer chains react fully to form a dense three-dimensional network cross-linking structure, which not only improves the cohesive strength but also effectively limits the swelling movement of polymer chain segments in the electrolyte.

[0016] An insulating tape for batteries, prepared by the above-described method, wherein the insulating tape comprises, by weight, the following components: 30-50 parts of flexible heat-resistant substrate, 40-60 parts of functional adhesive, 5-15 parts of insulating powder, and 1-5 parts of additives.

[0017] Specifically, the high-efficiency insulating powder is a compound system of nano-boron nitride coated with silane coupling agent and mica powder treated with flake treatment. The weight ratio of the two is 1:1-3, and the volume average particle size of the high-efficiency insulating powder is 0.5-5μm. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0019] The implementation of the present invention will be described in detail below with reference to specific embodiments.

[0020] Example 1 A method for preparing battery insulating tape specifically includes the following steps: S11. Adhesive preparation: Under controlled temperature and humidity, the adhesive, insulating powder and additives are put into a high-speed dispersion device and premixed under normal pressure. Then, the mixture is continuously dispersed for 30 minutes under vacuum of -0.05MPa and rotation speed of 1000r / min to obtain a homogeneous insulating adhesive. S12. Coating: The prepared insulating adhesive is quantitatively coated onto the pre-treated surface of the substrate using a micro-gravure coating method, and the thickness of the wet adhesive coating is controlled to be 20μm. S13. Preliminary drying: The coated substrate is sent into the first drying tunnel and baked at a temperature of 80-110℃ to dry the adhesive layer to obtain a semi-finished product after preliminary drying. S14. Heat curing: The semi-finished product after preliminary drying is sent into the second drying tunnel and heat-cured at 120-150℃ for 2 minutes. S15. Winding and Slitting: The fully cured and cooled tape is wound and slid to obtain the finished battery insulating tape.

[0021] In a temperature and humidity controlled environment (S11), adhesives, insulating powders, and additives are premixed in a high-speed dispersion device under normal pressure. The temperature and humidity controlled environment includes: Before preparing the adhesive, place the raw materials and equipment in a constant temperature and humidity clean room at 22℃ and relative humidity ≤50%RH for at least 4 hours to ensure that the physical properties of the adhesive and powder raw materials are stable before mixing, and prevent the insulating powder from absorbing moisture or the adhesive from pre-reacting due to excessive environmental humidity, so as to ensure the batch stability and shelf life of the final adhesive. In the premixing stage, the liquid adhesive should be pumped into the dispersion vessel first. After starting the stirring, the pre-dried insulating powder and additives should be slowly and evenly added under normal pressure and medium speed of 500 r / min. The feeding process should be controlled within 5 minutes. Then, continue stirring at the same speed for 10 minutes to allow the solid powder to be initially wetted and coated by the liquid, forming a suspension system.

[0022] High-speed dispersion equipment includes a high-speed planetary disperser with a jacket for circulating cooling water and a high-speed dispersion vessel with a vacuum-sealed lid. During vacuum dispersion, the material generates heat due to high-speed shearing. The cooling water in the jacket keeps the material temperature below 40°C to prevent the adhesive from cross-linking prematurely or the solvent from evaporating excessively and changing the formulation ratio. Obtaining a homogeneous insulating adhesive involves: after completing the specified dispersion time, stopping the machine, breaking the vacuum, taking a sample and coating it onto a glass plate for observation. Under a 100x magnifying glass, no visible undispersed powder particles or gel particles are observed, and the adhesive exhibits a homogeneous fluid state without bubble stratification. Simultaneously, its viscosity is measured using a rotational viscometer in a 25°C constant temperature water bath, and the reading should be stable within the range of 3000 cP, ensuring that the adhesive has good transferability and leveling properties in the subsequent microgravure coating process.

[0023] In step S12, the prepared insulating adhesive is quantitatively coated onto a pre-treated surface of the substrate using a microgravure coating method, including: The component used in the microgravure coating method for the prepared insulating adhesive is an anilox roller. The screen line count of the anilox roller is limited to 150 LPI, and the corresponding dot engraving depth is controlled at 30 μm. This allows for precise control of the amount of adhesive transferred per unit area, ensuring that the wet adhesive coating thickness is within 20 μm. The pre-treatment of the substrate refers to the single-sided surface modification treatment of the selected polyester film substrate before the coating process. Through corona treatment, the treatment power is set to 8kW and the electrode spacing is 1mm, so that the surface roughness Ra value of the treated surface reaches 0.1μm and the surface energy is increased to 50dyn / cm, which improves the spreading and anchoring effect of the adhesive.

[0024] Before the S12 coating operation, the prepared insulating adhesive must be filtered through a precision filter equipped with a 100-mesh stainless steel screen to remove trace mechanical impurities or large aggregates of powder that may be introduced during dispersion and transfer. During the quantitative coating process in S12, the operating parameters of the coating machine need to be linked and controlled to stabilize the coating speed within the range of 10m / min. Simultaneously, the angle and pressure of the doctor blade on the anilox roller are precisely adjusted to control it at 0.2MPa. At the same time, the substrate tension between the unwinding and coating sections is controlled in a closed loop by a tension sensor to ensure that the adhesive coating transferred from the anilox roller to the rough substrate is continuous, uniform, and without streaks.

[0025] In step S13, the coated substrate is fed into the first drying tunnel and baked at a controlled temperature of 80-110°C to allow the adhesive layer to dry to the surface, including: The first drying tunnel is a hot air circulating tunnel-type drying oven with a length between 8 and 15 meters and multiple independent temperature zones. Its internal hot air temperature adopts a gradient design, gradually increasing from the inlet end near the coating machine to the outlet end. The overall temperature increase is controlled at 80-110℃, which allows the solvent or water in the adhesive layer to evaporate slowly and fully from the surface to the inside, avoiding the formation of bubbles or coating collapse due to the internal solvent retention caused by the surface drying too quickly. The process goal of making the adhesive layer surface dry is that after 1 minute of baking in this stage, the fluidity of the adhesive layer surface disappears and a slight indentation remains that can slowly rebound. At this time, the adhesive layer still contains a small amount of residual solvent and has the ability to deform.

[0026] In S14, the pre-dried semi-finished product is sent to the second drying tunnel, where it undergoes heat curing treatment at 120-150℃ for 2 minutes, including: The second drying tunnel is an infrared radiation heating tunnel, which can provide uniform radiant heat, so that the inside and outside of the adhesive layer are heated to a constant high temperature of 120-150℃ at the same time, which is conducive to the thorough removal of internal solvents. Thermosetting treatment includes: using a constant high-temperature treatment environment to completely evaporate the 2% residual solvent or small molecule volatiles that remain deep in the adhesive layer after preliminary drying, so that the adhesive layer is completely densified. Moreover, the temperature range of the constant high-temperature treatment environment can effectively activate the chemical reactivity of the curing agent, promote full cross-linking reaction between adhesive molecules, and improve the cohesive strength, heat resistance and electrolyte resistance of the adhesive layer.

[0027] In S15, the fully cured and cooled tape is wound up and slit, including: The winding process is completed on a winding machine with a precision tension control system. The winding tension is automatically set and maintained at a constant 10N according to the width of the tape, ensuring that the tape is tightly wound and neatly rolled. The winding method adopts center winding, and at the same time as winding, a layer of non-stick release film must be simultaneously lined on the surface of the tape adhesive layer to prevent the layers of the tape from sticking together when stored in rolls. Slitting is a process in which large rolls of finished product are longitudinally slit according to a pre-set precise width on a high-speed CNC slitting machine. The smoothness of the slitting edges is monitored in real time during the slitting process to ensure that there are no burrs or glue layer flips.

[0028] An insulating tape for batteries, prepared by the above-described method, comprises, by weight: 30 parts of flexible heat-resistant substrate, 40 parts of functional adhesive, 5 parts of insulating powder, and 1 part of additives.

[0029] Specifically, the high-efficiency insulating powder is a compound system of nano-boron nitride coated with silane coupling agent and mica powder treated with flake treatment. The weight ratio of the two is 1:1, and the volume average particle size of the high-efficiency insulating powder is 0.5μm.

[0030] Example 2 A method for preparing battery insulating tape specifically includes the following steps: S11. Adhesive preparation: Under controlled temperature and humidity, the adhesive, insulating powder and additives are put into a high-speed dispersion device and premixed under normal pressure. Then, the mixture is continuously dispersed for 50 minutes under a vacuum of -0.07MPa and a rotation speed of 1500r / min to obtain a homogeneous insulating adhesive. S12. Coating: The prepared insulating adhesive is quantitatively coated onto the pre-treated surface of the substrate using a micro-gravure coating method, and the thickness of the wet adhesive coating is controlled to be 40μm. S13. Preliminary drying: The coated substrate is sent into the first drying tunnel and baked at a temperature of 80-110℃ to dry the adhesive layer to obtain a semi-finished product after preliminary drying. S14. Heat curing: The semi-finished product after preliminary drying is sent into the second drying tunnel and heat-cured at 120-150℃ for 3 minutes. S15. Winding and Slitting: The fully cured and cooled tape is wound and slid to obtain the finished battery insulating tape.

[0031] In a temperature and humidity controlled environment (S11), adhesives, insulating powders, and additives are premixed in a high-speed dispersion device under normal pressure. The temperature and humidity controlled environment includes: Before preparing the adhesive, the raw materials and equipment are placed in a constant temperature and humidity clean room at 23°C and relative humidity ≤50%RH for at least 4 hours to ensure that the physical properties of the adhesive and powder raw materials are stable before mixing, and to prevent the insulating powder from absorbing moisture or the adhesive from pre-reacting due to excessive environmental humidity, thus ensuring the batch stability and shelf life of the final adhesive. In the premixing stage, the liquid adhesive should be pumped into the dispersion vessel first. After starting the stirring, the pre-dried insulating powder and additives should be slowly and evenly added under normal pressure and medium speed of 600 r / min. The feeding process should be controlled within 6 minutes. Then, continue stirring at the same speed for 10 minutes to allow the solid powder to be initially wetted and coated by the liquid, forming a suspension system.

[0032] High-speed dispersion equipment includes a high-speed planetary disperser with a jacket for circulating cooling water and a high-speed dispersion vessel with a vacuum-sealed lid. During vacuum dispersion, the material generates heat due to high-speed shearing. The cooling water in the jacket keeps the material temperature below 40°C to prevent the adhesive from cross-linking prematurely or the solvent from evaporating excessively and changing the formulation ratio. Obtaining a homogeneous insulating adhesive involves: after completing the specified dispersion time, stopping the machine, breaking the vacuum, taking a sample and coating it onto a glass plate for observation. Under a 100x magnifying glass, no visible undispersed powder particles or gel particles are observed, and the adhesive exhibits a homogeneous fluid state without bubble stratification. Simultaneously, its viscosity is measured using a rotational viscometer in a 25°C constant temperature water bath, and the reading should be stable within the range of 5000 cP, ensuring that the adhesive has good transferability and leveling properties in the subsequent microgravure coating process.

[0033] In step S12, the prepared insulating adhesive is quantitatively coated onto a pre-treated surface of the substrate using a microgravure coating method, including: The component used in the microgravure coating method for the prepared insulating adhesive is an anilox roller. The anilox roller has a screen count of 200 LPI and controls the corresponding dot engraving depth to 50 μm. This allows for precise control of the amount of adhesive transferred per unit area, ensuring that the wet adhesive coating thickness is within the range of 40 μm. The pre-treatment of the substrate refers to the single-sided surface modification treatment of the selected polyester film substrate before the coating process. Through corona treatment, the treatment power is set to 12kW and the electrode spacing is 2mm, so that the surface roughness Ra value of the treated surface reaches 0.5μm and the surface energy is increased to 50dyn / cm, which improves the spreading and anchoring effect of the adhesive.

[0034] Before the S12 coating operation, the prepared insulating adhesive must be filtered through a precision filter equipped with a 150-mesh stainless steel screen to remove trace mechanical impurities or large aggregates of powder that may be introduced during dispersion and transfer. During the quantitative coating process in S12, the operating parameters of the coating machine need to be linked and controlled to stabilize the coating speed within the range of 20m / min. Simultaneously, the angle and pressure of the doctor blade on the anilox roller are precisely adjusted to control it at 0.3MPa. At the same time, the substrate tension between the unwinding and coating sections is controlled in a closed loop by a tension sensor to ensure that the adhesive coating transferred from the anilox roller to the rough substrate is continuous, uniform, and without streaks.

[0035] In step S13, the coated substrate is fed into the first drying tunnel and baked at a controlled temperature of 80-110°C to allow the adhesive layer to dry to the surface, including: The first drying tunnel is a hot air circulating tunnel-type drying oven with a length between 8 and 15 meters and multiple independent temperature zones. Its internal hot air temperature adopts a gradient design, gradually increasing from the inlet end near the coating machine to the outlet end. The overall temperature increase is controlled at 80-110℃, which allows the solvent or water in the adhesive layer to evaporate slowly and fully from the surface to the inside, avoiding the formation of bubbles or coating collapse due to the internal solvent retention caused by the surface drying too quickly. The process goal of making the adhesive layer surface dry is that after 2 minutes of baking in this stage, the fluidity of the adhesive layer surface disappears and a slight indentation remains that can slowly rebound. At this time, the adhesive layer still contains a small amount of residual solvent and has the ability to deform.

[0036] In S14, the pre-dried semi-finished product is sent to the second drying tunnel, where it undergoes heat curing treatment at 120-150℃ for 4 minutes, including: The second drying tunnel is an infrared radiation heating tunnel, which can provide uniform radiant heat, so that the inside and outside of the adhesive layer are heated to a constant high temperature of 120-150℃ at the same time, which is conducive to the thorough removal of internal solvents. Thermosetting treatment includes: using a constant high-temperature treatment environment to completely evaporate the 4% of residual solvent or small molecule volatiles that remain deep in the adhesive layer after initial drying, so that the adhesive layer is completely densified. Moreover, the temperature range of the constant high-temperature treatment environment can effectively activate the chemical reactivity of the curing agent, promote full cross-linking reaction between adhesive molecules, and improve the cohesive strength, heat resistance and electrolyte resistance of the adhesive layer.

[0037] In S15, the fully cured and cooled tape is wound up and slit, including: The winding process is completed on a winding machine with a precision tension control system. The winding tension is automatically set and maintained at a constant 40N according to the width of the tape, ensuring that the tape is tightly wound and neatly rolled. The winding method adopts center winding, and at the same time as winding, a layer of non-stick release film must be simultaneously lined on the surface of the tape adhesive layer to prevent the layers of the tape from sticking together when stored in rolls. Slitting is a process in which large rolls of finished product are longitudinally slit according to a pre-set precise width on a high-speed CNC slitting machine. The smoothness of the slitting edges is monitored in real time during the slitting process to ensure that there are no burrs or glue layer flips.

[0038] An insulating tape for batteries, prepared by the above-described method, comprises, by weight: 40 parts of flexible heat-resistant substrate, 50 parts of functional adhesive, 10 parts of insulating powder, and 3 parts of additives.

[0039] Specifically, the high-efficiency insulating powder is a compound system of nano-boron nitride coated with silane coupling agent and mica powder treated with flake treatment. The weight ratio of the two is 1:2, and the volume average particle size of the high-efficiency insulating powder is 3μm.

[0040] Example 3 A method for preparing battery insulating tape specifically includes the following steps: S11. Adhesive preparation: Under controlled temperature and humidity, the adhesive, insulating powder and additives are put into a high-speed dispersion device and premixed under normal pressure. Then, the mixture is continuously dispersed for 60 minutes under vacuum of -0.08MPa and rotation speed of 2000r / min to obtain a homogeneous insulating adhesive. S12. Coating: The prepared insulating adhesive is quantitatively coated onto the pre-treated surface of the substrate using a micro-gravure coating method, and the thickness of the wet adhesive coating is controlled to be 50μm. S13. Preliminary drying: The coated substrate is sent into the first drying tunnel and baked at a temperature of 80-110℃ to dry the adhesive layer to obtain a semi-finished product after preliminary drying. S14. Heat curing: The semi-finished product after preliminary drying is sent into the second drying tunnel and heat-cured at 120-150℃ for 5 minutes. S15. Winding and Slitting: The fully cured and cooled tape is wound and slid to obtain the finished battery insulating tape.

[0041] In a temperature and humidity controlled environment (S11), adhesives, insulating powders, and additives are premixed in a high-speed dispersion device under normal pressure. The temperature and humidity controlled environment includes: Before preparing the adhesive, place the raw materials and equipment in a constant temperature and humidity clean room at 25°C and relative humidity ≤50%RH for at least 4 hours to ensure that the physical properties of the adhesive and powder raw materials are stable before mixing, and prevent the insulating powder from absorbing moisture or the adhesive from pre-reacting due to excessive environmental humidity, thus ensuring the batch stability and shelf life of the final adhesive. In the premixing stage, the liquid adhesive should be pumped into the dispersion vessel first. After starting the stirring, the pre-dried insulating powder and additives should be slowly and evenly added under normal pressure and medium speed of 800 r / min. The feeding process should be controlled within 8 minutes. Then, continue stirring at the same speed for 10 minutes to allow the solid powder to be initially wetted and coated by the liquid, forming a suspension system.

[0042] High-speed dispersion equipment includes a high-speed planetary disperser with a jacket for circulating cooling water and a high-speed dispersion vessel with a vacuum-sealed lid. During vacuum dispersion, the material generates heat due to high-speed shearing. The cooling water in the jacket keeps the material temperature below 40°C to prevent the adhesive from cross-linking prematurely or the solvent from evaporating excessively and changing the formulation ratio. Obtaining a homogeneous insulating adhesive involves: after completing the specified dispersion time, stopping the machine, breaking the vacuum, taking a sample and coating it onto a glass plate for observation. Under a 100x magnifying glass, no visible undispersed powder particles or gel particles are observed, and the adhesive exhibits a homogeneous fluid state without bubble stratification. Simultaneously, its viscosity is measured using a rotational viscometer in a 25°C constant temperature water bath, and the reading should be stable within the range of 8000 cP, ensuring that the adhesive has good transferability and leveling properties in the subsequent microgravure coating process.

[0043] In step S12, the prepared insulating adhesive is quantitatively coated onto a pre-treated surface of the substrate using a microgravure coating method, including: The component used in the microgravure coating method for the prepared insulating adhesive is an anilox roller. The anilox roller has a screen count of 250 LPI and controls the corresponding dot engraving depth at 60 μm. This allows for precise control of the amount of adhesive transferred per unit area, ensuring that the wet adhesive coating thickness is within 50 μm. The pre-treatment of the substrate refers to the single-sided surface modification treatment of the selected polyester film substrate before the coating process. Through corona treatment, the treatment power is set to 15kW and the electrode spacing is 2mm, so that the surface roughness Ra value of the treated surface reaches 1.0μm and the surface energy is increased to 50dyn / cm, which improves the spreading and anchoring effect of the adhesive.

[0044] Before the S12 coating operation, the prepared insulating adhesive must be filtered through a precision filter equipped with a 200-mesh stainless steel screen to remove trace mechanical impurities or large aggregates of powder that may be introduced during dispersion and transfer. During the quantitative coating process in S12, the operating parameters of the coating machine need to be linked and controlled to stabilize the coating speed within the range of 30m / min. Simultaneously, the angle and pressure of the doctor blade on the anilox roller are precisely adjusted to control it at 0.5MPa. At the same time, the substrate tension between the unwinding and coating sections is controlled in a closed loop by a tension sensor to ensure that the adhesive coating transferred from the anilox roller to the rough substrate is continuous, uniform, and without streaks.

[0045] In step S13, the coated substrate is fed into the first drying tunnel and baked at a controlled temperature of 80-110°C to allow the adhesive layer to dry to the surface, including: The first drying tunnel is a hot air circulating tunnel-type drying oven with a length between 8 and 15 meters and multiple independent temperature zones. Its internal hot air temperature adopts a gradient design, gradually increasing from the inlet end near the coating machine to the outlet end. The overall temperature increase is controlled at 80-110℃, which allows the solvent or water in the adhesive layer to evaporate slowly and fully from the surface to the inside, avoiding the formation of bubbles or coating collapse due to the internal solvent retention caused by the surface drying too quickly. The process goal of making the adhesive layer surface dry is that after 3 minutes of baking in this stage, the fluidity of the adhesive layer surface disappears and a slight indentation remains that can slowly rebound. At this time, the adhesive layer still contains a small amount of residual solvent and has the ability to deform.

[0046] In S14, the pre-dried semi-finished product is sent to the second drying tunnel, where it undergoes heat curing treatment at 120-150℃ for 2-5 minutes, including: The second drying tunnel is an infrared radiation heating tunnel, which can provide uniform radiant heat, so that the inside and outside of the adhesive layer are heated to a constant high temperature of 120-150℃ at the same time, which is conducive to the thorough removal of internal solvents. Thermosetting treatment includes: using a constant high-temperature treatment environment to completely evaporate the 5% of residual solvent or small molecule volatiles that remain deep in the adhesive layer after initial drying, so that the adhesive layer is completely densified. Moreover, the temperature range of the constant high-temperature treatment environment can effectively activate the chemical reactivity of the curing agent, promote full cross-linking reaction between adhesive molecules, and improve the cohesive strength, heat resistance and electrolyte resistance of the adhesive layer.

[0047] In S15, the fully cured and cooled tape is wound up and slit, including: The winding process is completed on a winding machine with a precision tension control system. The winding tension is automatically set and maintained at a constant 50N according to the width of the tape, ensuring that the tape is tightly wound and neatly rolled. The winding method adopts center winding, and at the same time as winding, a layer of non-stick release film must be simultaneously lined on the surface of the tape adhesive layer to prevent the layers of the tape from sticking together when stored in rolls. Slitting is a process in which large rolls of finished product are longitudinally slit according to a pre-set precise width on a high-speed CNC slitting machine. The smoothness of the slitting edges is monitored in real time during the slitting process to ensure that there are no burrs or glue layer flips.

[0048] An insulating tape for batteries, prepared by the above-described method, comprises, by weight: 50 parts of flexible heat-resistant substrate, 60 parts of functional adhesive, 15 parts of insulating powder, and 5 parts of additives.

[0049] Specifically, the high-efficiency insulating powder is a compound system of nano-boron nitride coated with silane coupling agent and mica powder treated with flake treatment. The weight ratio of the two is 1:3, and the volume average particle size of the high-efficiency insulating powder is 5μm.

[0050] Comparison Example To clearly demonstrate the technological advancements of this invention, the following comparative experiments were designed. The control example (CE) represents commercially available common battery insulating tape prepared using traditional general formulas and conventional processes. Examples 1-3 are tapes prepared using the method described in this invention. The key performance test methods and results are compared in Tables 1-4 below: Table 1: Comparison of Core Materials and Structures Table 2: Comparison of Electrical Insulation Performance Table 3: Comparison of Thermal and Safety Performance Table 4: Comparison of Environmental Resistance and Durability The comparative experimental data in Tables 1-4 clearly demonstrate that the significant advancements and inventiveness of this invention compared to existing technologies include the following: 1. This invention constructs a three-in-one material system of "flame-retardant matrix - interface reinforcement - functional filler". The flame-retardant acrylic pressure-sensitive adhesive (EX1-3 LOI≥30%) fundamentally changes the flammable properties of the adhesive layer, realizing a qualitative change from "combustion promoter" to "flame retardant". It works synergistically with the substrate to achieve the highest flame retardant level of V-0, directly addressing the safety pain point of battery thermal runaway. The substrate, after surface roughening and activation treatment, improves the substrate-adhesive layer peel strength by about 50% (EX2 reaches 7.5 N / cm) through physical interlocking and chemical bonding, completely solving the hidden danger of interface delamination under long-term humid and hot environment. The nano boron nitride / mica composite system coated with silane coupling agent not only improves the dielectric strength to 82 kV / mm (EX2) through the "brick-mud" structure, far exceeding the 45 kV / mm of the control example, but also improves the thermal conductivity by more than double. 2. In tests simulating the harsh internal environment of a battery, its electrolyte resistance (peel strength retention rate >85%) and insulation stability after high temperature and high humidity aging (insulation resistance >800 MΩ) are several times higher than the control example. This proves that the surface-treated compound insulating powder effectively blocks electrolyte penetration and erosion; the fully cross-linked flame-retardant polymer network and the stable interface combination together build a solid defense against damp heat aging and chemical corrosion, meeting the reliability requirements of power batteries with a service life of more than ten years. 3. Vacuum high-speed dispersion and cooling temperature control ensure that functional powders are uniformly dispersed at the nano / micro scale without defect aggregation, which is the structural basis for achieving high insulation and high thermal conductivity. Microgravure coating with specific parameters at 150-250 LPI and a stepped gradient curing process achieves precise control of the adhesive layer thickness and density, avoiding microscopic defects such as pinholes and internal stress, ensuring extreme uniformity of product performance and batch stability. The high consistency of the data in the examples demonstrates the superiority of this process.

[0051] In summary, this invention, through innovation across the entire chain from molecular interface design to macroscopic process control, solves the inherent defects of traditional battery insulating tapes in terms of insulation strength, flame retardant safety, long-term weather resistance, and interface reliability, and provides a highly reliable, long-life battery insulating tape solution with significantly superior overall performance compared to existing technologies.

[0052] This technical solution significantly enhances the mechanical and chemical bonding between the substrate and the adhesive layer by employing a corona-treated, single-sided roughened substrate, effectively preventing delamination. A flame-retardant acrylic pressure-sensitive adhesive with a limiting oxygen index ≥28% is designed as the adhesive, imparting flame retardancy to the adhesive layer itself and achieving V-0 flame retardancy standards in synergy with the substrate. Furthermore, a nano-boron nitride / mica powder composite system coated with a silane coupling agent is introduced as the insulating powder, improving dielectric strength, thermal conductivity, and density. Through a highly refined and parameter-controllable preparation process, material innovation is transformed into stable and superior product performance. Vacuum high-speed dispersion and cooling temperature control ensure highly homogeneous and defect-free dispersion of the insulating powder in the adhesive. Specific 150-250 LPI, 30-60 μm parameters for microgravure coating, combined with stepped gradient drying and segmented thermosetting processes, achieves precise control of the adhesive layer thickness, gradual and complete solvent evaporation, and full cross-linking reaction. This not only ensures extremely high consistency between product batches but also maximizes the functionality of each component.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an insulating tape for batteries, characterized in that, Specifically, the following steps are included: S11. Adhesive preparation: Under controlled temperature and humidity, the adhesive, insulating powder and additives are put into a high-speed dispersion device and premixed under normal pressure. Then, the mixture is continuously dispersed for 30-60 minutes under a vacuum of -0.05 to -0.08 MPa and a rotation speed of 1000-2000 r / min to obtain a homogeneous insulating adhesive. S12. Coating: The prepared insulating adhesive is quantitatively coated onto the pre-treated surface of the substrate using a micro-gravure coating method, and the thickness of the wet adhesive coating is controlled to be 20-50μm. S13. Preliminary drying: The coated substrate is sent into the first drying tunnel and baked at a temperature of 80-110℃ to dry the adhesive layer to obtain a semi-finished product after preliminary drying. S14. Heat curing: The semi-finished product after preliminary drying is sent into the second drying tunnel and heat-cured at 120-150℃ for 2-5 minutes. S15. Winding and Slitting: The fully cured and cooled tape is wound and slid to obtain the finished battery insulating tape.

2. The method for preparing a battery insulating tape as described in claim 1, characterized in that, In a temperature and humidity controlled environment (S11), adhesives, insulating powders, and additives are premixed in a high-speed dispersion device under normal pressure. The temperature and humidity controlled environment includes: Before preparing the adhesive, the raw materials and equipment are placed in a constant temperature and humidity clean room at a temperature of 23±2℃ and a relative humidity of ≤50%RH for at least 4 hours to ensure that the physical properties of the adhesive and powder raw materials are stable before mixing, and to prevent the insulating powder from absorbing moisture or the adhesive from undergoing a pre-reaction due to excessive environmental humidity, thus ensuring the batch stability and shelf life of the final adhesive. In the premixing stage, the liquid adhesive is first pumped into the dispersion vessel. After stirring is started, the pre-dried insulating powder and the additives are slowly and evenly added under normal pressure and medium speed of 500-800 r / min. The feeding process should be controlled within 5-8 minutes. Then, the stirring speed is maintained for another 10 minutes to allow the solid powder to be initially wetted and coated by the liquid, forming a suspension system.

3. The method for preparing a battery insulating tape as described in claim 2, characterized in that, The high-speed dispersion equipment includes a high-speed planetary disperser with a jacket for circulating cooling water and a high-speed dispersion vessel with a vacuum-sealed lid. During the vacuum dispersion process, the material generates heat due to high-speed shearing. The cooling water in the jacket keeps the material temperature below 40°C to prevent the temperature from being too high, which could cause the adhesive to cross-link prematurely or the solvent to evaporate excessively and change the formula ratio. Obtaining a homogeneous insulating adhesive involves: after completing the specified dispersion time, stopping the machine, breaking the vacuum, taking a sample and coating it onto a glass plate for observation. Under a 100x magnifying glass, no visible undispersed powder particles or gel particles are observed, and the adhesive exhibits a homogeneous fluid state without bubble stratification. Simultaneously, its viscosity is measured using a rotational viscometer in a 25°C constant temperature water bath, and the reading should be stable within the range of 3000-8000 cP, ensuring that the adhesive has good transferability and leveling properties in the subsequent microgravure coating process.

4. The method for preparing a battery insulating tape as described in claim 3, characterized in that, In step S12, the prepared insulating adhesive is quantitatively coated onto a pre-treated surface of the substrate using a microgravure coating method, including: The component used in the microgravure coating method for the prepared insulating adhesive is an anilox roller. The anilox roller has a screen count of 150-250 LPI and controls the corresponding dot engraving depth to be 30-60 μm. This allows for precise control of the amount of adhesive transferred per unit area, ensuring that the wet adhesive coating thickness is within the range of 20-50 μm. The pre-treatment of the substrate refers to the single-sided surface modification treatment of the selected polyester film substrate before the coating process. Through corona treatment, the treatment power is set to 8-15kW and the electrode spacing is 1-2mm, so that the surface roughness Ra value of the treated surface reaches 0.1-1.0μm and the surface energy is increased to 50dyn / cm, which improves the spreading and anchoring effect of the adhesive.

5. The method for preparing a battery insulating tape as described in claim 4, characterized in that, Before the S12 coating operation, the prepared insulating adhesive must be filtered through a precision filter equipped with a 100-200 mesh stainless steel filter to remove trace mechanical impurities or large aggregates of powder that may be introduced during dispersion and transfer. During the quantitative coating process in S12, the operating parameters of the coating machine need to be controlled in a coordinated manner to stabilize the coating speed within the range of 10-30m / min. Simultaneously, the angle and pressure of the doctor blade on the anilox roller are precisely adjusted to control the pressure within the range of 0.2-0.5MPa. At the same time, the substrate tension between the unwinding and coating sections is controlled in a closed loop by a tension sensor to ensure that the adhesive coating transferred from the anilox roller to the rough substrate is continuous, uniform, and without streaks.

6. The method for preparing a battery insulating tape as described in claim 5, characterized in that, In step S13, the coated substrate is fed into the first drying tunnel and baked at a controlled temperature of 80-110°C to allow the adhesive layer to dry to the surface, including: The first drying tunnel is a hot air circulating tunnel-type drying oven with a length between 8 and 15m and multiple independent temperature zones. Its internal hot air temperature adopts a gradient design, gradually increasing from the inlet end near the coating machine to the outlet end. The overall temperature increase is controlled at 80-110℃, so that the solvent or water in the adhesive layer can evaporate slowly and fully from the surface to the inside, avoiding the formation of bubbles or coating collapse due to the internal solvent retention caused by the surface drying too fast. The process goal of making the adhesive layer surface dry is that after baking for 1-3 minutes in this stage, the fluidity of the adhesive layer surface disappears and a slight indentation is left that can slowly rebound. At this time, the adhesive layer still contains a small amount of residual solvent and has the ability to deform.

7. The method for preparing a battery insulating tape as described in claim 6, characterized in that, In S14, the pre-dried semi-finished product is sent to the second drying tunnel, where it undergoes heat curing treatment at 120-150℃ for 2-5 minutes, including: The second drying tunnel is an infrared radiation heating tunnel, which can provide uniform radiant heat, so that the inside and outside of the adhesive layer are heated to a constant high temperature of 120-150℃, which is conducive to the thorough removal of internal solvents. The thermosetting process includes: using a constant high-temperature treatment environment to completely evaporate the 2-5% residual solvent or small molecule volatiles that remain deep in the adhesive layer after preliminary drying, so that the adhesive layer is completely densified. Moreover, the temperature range of the constant high-temperature treatment environment can effectively activate the chemical reactivity of the curing agent, promote the full cross-linking reaction between adhesive molecules, and improve the cohesive strength, heat resistance and electrolyte resistance of the adhesive layer.

8. The method for preparing a battery insulating tape as described in claim 7, characterized in that, In S15, the fully cured and cooled tape is wound up and slit, including: The winding process is completed on a winding machine with a precision tension control system. The winding tension is automatically set and maintained at a constant 10-50N according to the width of the tape, ensuring that the tape is tightly wound and neatly rolled. The winding method adopts center winding, and at the same time as winding, a layer of anti-stick release film must be simultaneously lined on the surface of the tape adhesive layer to prevent the layers of the tape from sticking together when stored in rolls. The slitting process involves longitudinally dividing the large roll of finished product into strips according to a pre-set precise width on a high-speed CNC slitting machine. The smoothness of the slitting edges is monitored in real time during the slitting process to ensure that there are no burrs or glue layer flips.

9. A battery insulating tape, characterized in that, The insulating tape, prepared by the preparation method according to any one of claims 1-8, comprises, by weight, the following components: 30-50 parts of flexible heat-resistant substrate, 40-60 parts of functional adhesive, 5-15 parts of insulating powder, and 1-5 parts of additives.

10. The battery insulating tape as described in claim 9, characterized in that, The high-efficiency insulating powder is a compound system of nano-boron nitride coated with silane coupling agent and mica powder treated with flake treatment. The weight ratio of the two is 1:1-3, and the volume average particle size of the high-efficiency insulating powder is 0.5-5μm.

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